Sheriff's officials in Seminole, Osceola, Volusia, Lake and Brevard counties say they are all in the same pickle -- more prisoners than space to accommodate them. But some counties are undertaking major expansion.

The Seminole County jail is running about 25 percent over its limit of 236 inmates imposed by the state Department of Corrections. Conditions will improve in late 1987 when a 480-bed expansion and renovation to the jail for $13 million are completed.

Because of crowding, the jail hasn't passed a state inspection since June 1982. When the 244 bunks are filled, inmates sleep on floor mats, a violation of state standards.

Despite state and federal court pressure to contain crowding, Sheriff John Polk vows to stand by his pledge to continue holding federal prisoners for the U.S. Marshal's office, which pays the county about $300,000 a year to do so.

The federal government has provided $300,000 toward the cost of expanding the jail, and $700,000 more is awaiting congressional approval. To get the $300,000, the county had to agree to hold 30 federal prisoners a day for five years. If the county gets the additional $700,000, the county must agree to house an additional 66 federal prisoners a day.

Polk has reduced the number of federal prisoners he will accept from 50 to 35 a day, but said a further cutback would put too much of a squeeze on the marshal's office.

The state sued the county commissioners and Polk in October, seeking a court-imposed inmate limit that would give the sheriff more authority to reduce crowding. The sheriff and county commissioners have filed motions to dismiss the suit.

The state has filed similar ''friendly'' suits against most other Central Florida counties.

A committee of Seminole County judges, prosecutors and jail administrators meet monthly to consider releasing the more deserving inmates. About 20 have been freed since last summer.

Expanding the jail and devising alternatives to confining prisoners are the only long-term solutions, Polk said.

By September, the new dormitory pods and support buildings will be completed and inmates will be moved into the new jail space while the old jail is renovated. Those renovations should be competed by the fall of 1987, bringing the jail capacity to 716.

Another 300-bed jail expansion for $6.6 million will be needed by the early 1990s. That should serve the county's needs through the year 2000, according to jail consultants. With the opening of a 256-bed facility in November, Orange County has space for about 1,265 prisoners in its three jails. The county's jail population has hovered between 1,250 and 1,300 for more than a year.

Until the new jail opened, the county normally had 200 to 300 prisoners sleeping on mattresses on the floor on any given night for the last year.

In February, a 160-bed jail is scheduled to open, giving the county 1,425 beds, more than enough space for its current population. Both jails are part of an $87 million jail construction program expected to be finished by 1991. The Orange County Commission approved the program in 1981 in answer to a state lawsuit and a class-action lawsuit filed in federal court by inmates over jail conditions.

When construction is finished, the county will have between 1,800 and 1,900 cells, which is expected to meet the need for space indefinitely.

Osceola County's jail, designed to house 52 prisoners, averages 109 and ''it's been running this way for a long time,'' said sheriff's Sgt. Patrice Schmook.

Construction of a new sheriff's office and 208-bed jail is nearly complete, with land available for expansion.

The court-ordered capacity of the Volusia County jail and the Tomoka Correctional Institution near Daytona Beach is 559, but they average about 200 over the limit. Inmates successfully filed suit in 1978. A committee is set up to consider releasing inmates.

The county is spending $18 million for a new 600-bed jail near Tomoka.

Brevard County is under a court-ordered limit of 237 inmates, but it's running about 275.

''We've been overcrowded for a while,'' said sheriff's Sgt. Elizabeth Canada. The one-year-old limit is exceeded about five months of the year.

A committee of judges, prosecutors and public defenders reviews cases to decide who might be released, but Canada said it's difficult because most are felons.

The county is spending $15 million for a 384-bed facility in north Brevard scheduled for completion in August, but consultants recommend it be expanded by 200 beds.

The state limit for Lake County is 120, but the population runs 165 to 170. The county is not under a court-ordered limit. A new jail is being considered, but that's about as far as it's gone.

It's the same story in Polk County: state-imposed limit of 394, jail population of about 600.

That prompted Chief Circuit Judge William A. Norris Jr. to mail a letter Jan. 9 to Florida sheriffs that gives other agencies 72 hours to pick up their suspects apprehended in Polk.

''We're in a terrible pinch,'' Norris said.

A new 120-bed facility is nearing completion and plans are under way to add 400 beds.